Rotating-slide vacuum pump or compressor of block design having a disc-rotor synchronous motor which is mounted on flying bearings

ABSTRACT

In a rotating-slide vacuum pump or compressor having a rotor ( 6 ) which can rotate in a housing ( 2 ) and is driven by a drive shaft, and having slides ( 8 ) which can be moved outwards in the circumferential direction herein in slots ( 7 ) in the rotor ( 6 ) and separate individual feed chambers of a working area ( 9 ), which is provided with an intake opening ( 1 ) and an outlet opening, from one another, and each assume a maximum outer position adjacent to the housing inner wall, driven by centrifugal force, the arrangement is designed such that a brushless disc-rotor synchronous motor ( 11, 12 ) is fitted in the axial direction to the rotor shaft.

This application is a National Stage filing under 35 U.S.C. § 371 of PCTApplication No. PCT/EP2007/007151 filed Aug. 13, 2007, which claimspriority from German Application No. DE 10 2006 039 958.7 filed Aug. 25,2006.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to rotating slide vacuum pumps and compressors asclaimed in the precharacterizing clause of claim 1.

2. Description of Related Art

The invention may relate both to rotating slide vacuum pumps andcompressors which are lubricated by oil circulation and to those whichrun dry. These pumps and compressors are normally designed to behorizontal, with the slides, which can move in the rotor, in the case ofdry-running rotating slide vacuum pumps and compressors normally beingcomposed of graphite or graphite composite materials while, in the caseof rotating slide vacuum pumps and compressors which are lubricated byoil circulation, the slides may also be composed of plastic or plasticcomposite materials.

Rotating slide vacuum pumps and compressors which are lubricated by oilcirculation and which are of block design, that is to say with a rotorwhich is mounted on flying bearings, are normally operated withsingle-phase alternating-current motors or three-phase asynchronousmotors. Pumps and compressors such as these have been successfully usedfor decades and are subject to severe competition in the widelydiffering markets.

Single-shaft rotating slide vacuum pumps and compressors which arelubricated by oil circulation are of block design only for low feedrates, that is to say from about 2 m³/h to a maximum of 100 m³/h. Abovethese feed rates, the surface area of the pumps and compressors is nolonger adequate for thermal emission of the compression heat. Largervacuum pumps and compressors are therefore designed primarily in aconventional manner with a coupling between the drive motor and the pumpor compressor stage.

Prior art throughout the world is the use of alternating-current orthree-phase drives which, because of the small gaps that are requiredbetween the rotor and the cylindrical housing which is permanentlyfitted on the drive-end bearing plate of the motor, requirescomparatively complex fine tuning of the motor bearing. The drivemotors, particularly in the case of high-quality vacuum pumps andcompressors, are therefore subject not only to the described fine tuningbut, furthermore, they must comply with the required accuracies with thequality remaining unchanged. This results in high costs and a restrictedprovider market for motors such as these.

Furthermore, particularly in the power range from 80 W to 2 kW that isused here, the relatively low efficiency of alternating-current drivesand of three-phase drives not only results in a noticeably largerphysical volume but, in addition, the feasible physical space cannot beoptimally utilized because of the need for an elongated physical shape.

The described rotating slide vacuum pumps and compressors which arelubricated by oil circulation and are of block design can in principlebe subdivided into two further variants, specifically,

1) rotating slide vacuum pumps and compressors which are lubricated byoil circulation and with an oil mist separator arranged at the side ofthe pump/compressor stage and motor. Owing to the larger externalsurface area, this embodiment can be used for all physical sizes, thatis to say from about 2 m³/h up to a maximum of 100 m³/h. Furthermore,the oil mist separator can use all its external surfaces, except for theinner area of the gas inlet flange to the pump/compressor stage, forheat emission to the outside, and

2) rotating slide vacuum pumps and compressors which are lubricated byoil circulation and have an oil mist separator which is arranged axiallywith respect to the pump/compressor stage. In the case of this design,one of the axial housing covers is the drive-end motor plate itself,while the other axial housing cover is connected directly to the oilmist separator, as a result of which the drive motor, thepump/compressor stage and the oil mist separator are arranged directlyadjacent to one another axially. However, this means that one of themajor outer surfaces is not available to the oil mist separator and/orto the pump/compressor stage for heat emission. For this reason, andbecause this embodiment also has an excessive ratio of length (at itsaxial extent) to width of the base area, for many applications, machinessuch as these are produced primarily only in sizes from about 2 m³/h upto a maximum of 12 m³/h.

In the case of small rotating slide vacuum pumps and compressors whichare lubricated by oil circulation, one problem that frequently occurseven during production is that, as a consequence of the flying bearingsof the rotor, the gaps (of between 0.02 and 0.04 mm) which are narrowand the relatively high radial forces on the rotor during test running,noise is produced which may also be caused, inter alia, by touchingbetween the stationary housing and the rotor, and this noise isunacceptable for the user.

The invention is therefore based on the object of designing rotatingslide vacuum pumps and compressors of this generic type in order toovercome the described disadvantages, such that the overall physicalsize of the machine is minimized, the process reliability duringproduction is increased and, at the same time, the assembly of themachine is lastingly simplified.

SUMMARY OF THE INVENTION

The features of the invention which is being created in order to solvethis problem result from claim 1. Advantageous refinements are describedin the further claims.

Bearing in mind the problems and deficiencies of the prior art, it istherefore an object of the present invention to provide a rotating slidevacuum pump lubricated by oil circulation and having a block design,with a disk-rotor synchronous motor, which is mounted on flyingbearings.

The present invention is directed to, in a first aspect, a rotatingslide vacuum pump or compressor including a rotor, which can rotate in ahousing and is driven by a drive shaft, and slides which can be movedoutward in the circumferential direction herein in slots in the rotor,which separate individual feed chambers of a working area, which isprovided with an induction opening and an outlet opening, from oneanother and, driven by centrifugal force, each occupy a maximum outerposition on the housing inner wall, comprising a brushless disk-rotorsynchronous motor which is fitted in the axial direction on the rotorshaft, wherein thermal isolation is incorporated in the form of ahousing constriction between the pump/compressor stage and thedisk-rotor synchronous motor or is provided by the housing shape itself.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the invention believed to be novel and the elementscharacteristic of the invention are set forth with particularity in theappended claims. The figures are for illustration purposes only and arenot drawn to scale. The invention will be explained in more detail inthe following text with reference to the drawing, in which:

FIG. 1 shows a rotating slide vacuum pump which is designed according tothe invention, is lubricated by oil circulation and has a block design,with a disk-rotor synchronous motor, which is mounted on flyingbearings, schematically in the form of a longitudinal section, and

FIG. 2 shows a cross section along the line II-II in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

In describing the preferred embodiment of the present invention,reference will be made herein to FIGS. 1-2 of the drawings in which likenumerals refer to like features of the invention.

The invention covers rotating slide vacuum pumps and compressors ofblock design which are mounted on flying bearings, run dry or,preferably, are lubricated by oil circulation, with an oil mistseparator which is fitted parallel, that is to say at the side oraxially, with respect to the common motor and pump/compressor shaft.

According to the invention, the bearing is moved from the motor to thepump/compressor stage, that is to say the motor itself is mounted eitherby a plain bearing or by needle bearings directly in the housing coversof the pump/compressor stage, with a disk-rotor synchronous motor, whichis mounted on flying bearings, and has a brushless rotor, being used asthe drive. The arrangement with two stator disks, in each case one onone of the end faces of the disk rotor which is fitted with permanentmagnets compensate virtually completely for the axial forces, thusrendering support by an axial bearing superfluous.

This surprisingly simple arrangement according to the invention not onlysignificantly minimizes the overall physical size of the pump or of thecompressor and achieves the required accuracy for rotor guidance, butalso achieves an efficiency improvement of the motor from about 75 to80% to 85 to 95%. This means that there is no need for direct cooling ofthe motor by a motor fan.

Finally, the arrangement according to the invention results in asimplification of the logistic handling of the vacuum pumps andcompressors, to be precise in that as a result of the use of simpleelectronic closed-loop control and so-called multi-voltage power supplyunits, the complexity, that is to say the range of variants of motorsfor each physical size, is reduced from more than 20 variants in thepast down to one variant.

The invention is thus based on the idea of fitting a brushlessdisk-rotor synchronous motor in the axial direction on the rotor shaft.In one refinement of the invention, this may either have a stator whichis fitted on both sides with respect to the disk rotor, for the purposeof axial force compensation, or else may be provided with only onestator which is fitted on one side with respect to the disk rotor, andin which the axial forces which occur are then absorbed by an axialbearing.

Particular advantages are achieved when, according to the invention,thermal isolation is incorporated in the form of a housing constrictionbetween the pump/compressor stage and the disk-rotor synchronous motoror is provided by the housing shape itself.

It is within the scope of the invention that a Hall sensor is providedfor position identification for closed-loop control.

In a development of the invention, it is possible to provide that an oilmist separator is arranged around the housing of the pump/compressorstage so as to achieve a minimal physical space overall, with a squarebase area.

Finally, according to the invention, it is possible to provide a fan tobe arranged opposite the disk-rotor synchronous motor on the rotorshaft, by means of which the compression heat is dissipated from themachine.

Alternatively or additionally, a fan impeller is fitted on the rotorshaft, on the side opposite the disk-rotor synchronous motor, withrespect to the pump/compressor stage, and is used for cooling thepump/compressor stage with cooling air.

As can be seen from the drawing, in the case of the illustrated rotatingslide vacuum pump which is lubricated by oil circulation, the feedmedium is inducted via an induction opening 1 tangentially into theworking area 9 of a housing 2, and is fed axially through one or moreholes 3 to an oil mist separator 4.

This oil mist separator 4 is flange-connected directly to thepump/compressor stage via a housing intermediate cover 5. In the oilmist separator 4, the feed medium is passed to an air oil-extractionelement 15 and then to the gas outlet 16.

A rotor 6, which is arranged in the housing 2, is provided with aplurality of slide slots 7 which, as can be seen in FIG. 2, areincorporated radially or else off-axis, externally in the rotor 6.Slides 8 are arranged such that they can be moved in the slide slots 7.These slides 8 separate individual feed chambers of the working area 9from one another.

The housing 2 is bounded by the intermediate cover 5 on its left-handside as shown in FIG. 1, and is bounded by a further cover 10 on itsright-hand side as shown in FIG. 1. The housing of a brushlessdisk-rotor motor is fitted to the outside of the housing cover 10 andhas a brushless disk rotor 11, which is fitted with permanent magnets,as well as two stator disks 12 in which multipole electrical windingsare located. The position sensor which is required for the motorregulator for driving the motor windings is not illustrated in any moredetail in the drawing.

The single bearing for the entire rotor 6 is provided by needle bearings13 in the illustrated example embodiment. Instead of this, it is, ofcourse, also possible to use plain bearings instead of the needlebearings 13.

The motor area is sealed by a conventional radial shaft sealing ring 14.

With regard to features of the invention which are not explained in anymore detail above, reference is furthermore expressly made to thedrawing and to the claims.

1. A rotating slide vacuum pump or compressor including a rotor, whichcan rotate in a housing and is driven by a drive shaft, and slides whichcan be moved outward in the circumferential direction herein in slots inthe rotor, which separate individual feed chambers of a working area,which is provided with an induction opening and an outlet opening, fromone another and, driven by centrifugal force, each occupy a maximumouter position on the housing inner wall, comprising a brushlessdisk-rotor synchronous motor which is fitted in the axial direction onthe rotor shaft, wherein thermal isolation is incorporated in the formof a housing constriction between the pump/compressor stage and thedisk-rotor synchronous motor or is provided by the housing shape itself.2. The vacuum pump or compressor of claim 1, wherein the disk-rotorsynchronous motor includes a stator which is fitted on both sides withrespect to the disk rotor, for the purpose of axial force compensation.3. The vacuum pump or compressor of claim 1, wherein the disk-rotorsynchronous motor includes a stator which is fitted on one side withrespect to the disk rotor and in which the axial forces which occur areabsorbed by an axial bearing.
 4. The vacuum pump or compressor of claim1, including a Hall sensor, which is provided for positionidentification for closed-loop control.
 5. The vacuum pump or compressorof claim 1, including an oil mist separator arranged around the housingof the pump/compressor stage so as to achieve a minimal physical spaceoverall, with a square base area.
 6. The vacuum pump or compressor ofclaim 1, including a fan arranged opposite the disk-rotor synchronousmotor on the rotor shaft in order to dissipate compression heat from themachine.
 7. The vacuum pump or compressor of claim 1, comprising a fanimpeller fitted on the rotor shaft, on the side opposite the disk-rotorsynchronous motor, with respect to the pump/compressor stage, and isused for cooling the pump/compressor stage with cooling air.
 8. Thevacuum pump or compressor of claim 2, including a Hall sensor, which isprovided for position identification for closed-loop control.
 9. Thevacuum pump or compressor of claim 3, including a Hall sensor, which isprovided for position identification for closed-loop control.
 10. Thevacuum pump or compressor of claim 2, including an oil mist separatorarranged around the housing of the pump/compressor stage so as toachieve a minimal physical space overall, with a square base area. 11.The vacuum pump or compressor of claim 4, including an oil mistseparator arranged around the housing of the pump/compressor stage so asto achieve a minimal physical space overall, with a square base area 12.The vacuum pump or compressor of claim 2, including a fan arrangedopposite the disk-rotor synchronous motor on the rotor shaft in order todissipate compression heat from the machine.
 13. The vacuum pump orcompressor of claim 4, including a fan arranged opposite the disk-rotorsynchronous motor on the rotor shaft in order to dissipate compressionheat from the machine.
 14. The vacuum pump or compressor of claim 5,including a fan arranged opposite the disk-rotor synchronous motor onthe rotor shaft in order to dissipate compression heat from the machine.15. The vacuum pump or compressor of claim 2, comprising a fan impellerfitted on the rotor shaft, on the side opposite the disk-rotorsynchronous motor, with respect to the pump/compressor stage, and isused for cooling the pump/compressor stage with cooling air.
 16. Thevacuum pump or compressor of claim 3, comprising a fan impeller fittedon the rotor shaft, on the side opposite the disk-rotor synchronousmotor, with respect to the pump/compressor stage, and is used forcooling the pump/compressor stage with cooling air.
 17. The vacuum pumpor compressor of claim 4, comprising a fan impeller fitted on the rotorshaft, on the side opposite the disk-rotor synchronous motor, withrespect to the pump/compressor stage, and is used for cooling thepump/compressor stage with cooling air.
 18. The vacuum pump orcompressor of claim 5, comprising a fan impeller fitted on the rotorshaft, on the side opposite the disk-rotor synchronous motor, withrespect to the pump/compressor stage, and is used for cooling thepump/compressor stage with cooling air.
 19. The vacuum pump orcompressor of claim 6, comprising a fan impeller fitted on the rotorshaft, on the side opposite the disk-rotor synchronous motor, withrespect to the pump/compressor stage, and is used for cooling thepump/compressor stage with cooling air.